CH 25 Notes

Animal Kingdom

Characteristics

• Multicellular
• eukaryotic--have nucleus
• specialized cells and tissues
• heterotrophic-consumer
• capable of movement/responding to stimuli

Body of Development
Stages of Development

• Blastula: a hollow ball of cells that develop from the zygote
• Gastrula: two layered structrue that develops from the blastula and gives rise to germ cell layers

• Endoderm: Inner most germ cell layers ex. digestive organs
• Mesoderm: Middle germ cell layer ex. muscles and circulatory systems
• Extoderm: Outer most germ cell layer, ex. skin, nervous system

Symmetry:
Assymetry: irregularly shaped body (no symmetry)
ex. sponges

Radial symmetry:
Circular organization; appears to be the same from any angle--can be divided along any plane through a central axis into equal halves
ex. starfish; hydra

Bilateral Symmetry: can be divided down length into right and left halves
ex. humans

Body plans

• Acdolomates: have no true body cavities
  • ex. flatworms
• Pseudocoelomates: have body cavities that are only partially lined iwth mesoderm
  • ex. roundworms
• Coelomates: have tru body cavities completely lined by mesoderm
  • ex. segmented worms, humans, insects, fishes

Classification

• Invertebrates: animals without a backbone; many have an exoskeleton
  • ex. jellyfish, worms, clams, spiders, etc.
  • 95% of all animals are invertebrates, insects make up the largest of that; 8 phyla

• Vertebrates: animals that have a backbone, an endoskeleton, and are bilaterally symmetrical
  • ex. fish, amphibians, reptiles, birds, and mammals

Adaptations of Land Animals
Skeleton Systems
Reproduction:
Returning to water to lay eggs or secreting protective shells over eggs or developing eggs within bodies